Paper manufacture



Patented Feb. 14, 1933 HAROLD ROBERT BAI'TON, 0F ANDOVETR, MASSACHUSETTS, ASSIGNOR T0 RAIFFOLD PATENT OFFICE PROCESS CORPORATION, A CORPORATION DF MASSACHUSETTS PAPER MANUFACTURE No Drawing. Application filed May 1,

This invention relates to the manufacture of paper filled with alkaline filler.

The principal object of this invention is to provide an improved method of manufacturing paper filled with alkaline filler Wherein size is employed. V

An important object is to provide an improved method of manufacturing paper filled with alkaline filler wherein material later to serve as a size precipitant is employed in the beater and alkaline filler and size are added at the dilute stage of the paper making operation.

A further object is the use of a procedure whereby the proportion of size used in an alkaline'filler paper mix is susceptible to speedy adjustment.

@ther objects andadvantages of my invention will become apparent during the course of the following description.

In my copending application Serial No.

304,167, filed September 5, 1928, novv matured into Patent No. 1,803,642, issued May 5, 1931, l have described a. method of sizing paper filled with an alkaline tiller wherein an slimline filler is added to a sized fibrous mix at the wet end of the paper machine. Moreover, in copending application Serial No. 321,753, riled November 2-1 1928,110W matured into Patent No. 1,808,070, issued June 2, i031, l have described a procedure wherein substantially unsized paper filled with alkaline filler is made by adding alum. and ii" desired an amount of size insuilicient to impart a substantial degree of sizing to the resulting paper, in the beater and alkaline tiller at the net end of the paper machine.

l have now found that similar results may be obtained by a somewhat difierent method. This method is by adding alum to the fibrous material in the heater and adding the size and the alkaline filler under conditions "farce the minimizing oi the time and/or intimacy of contact of the constituents of the mix, e. g. at the wetend of the paper machine. Under certain conditions this method of operation is preferable to those disclosed in any cited copending applications. For eX-' ample, as the size is added at the Wetend of 5 the paper machine, there is thus provided a 1931. Serial No. 534,461.

method by which the amount of sizing in the furnish can be adjusted very much more quickly than where the size is added in the beater. Another advantage is that Where unsized paper is made there are certain times, when the stock is running very satisfactorily on the machine, Where it appears to be unnecessary to continue the addition of a small amount of size, and in such case the size being added at the wet end of the paper machine can be discontinued at once; and also can beintroduced immediately if trouble begins Without Waiting for the time interval that would be required to elapse if the sizing were introduced in the beater.

In the preferred practice of my invention 1 add alum to fibrous material in a heater, which should contain substantially no alkaline tiller either added as such or admixed with the fibre. Then after the mix has passed through the subsequent chests, and refining machinery if desired, it is ready to be diluted at the mixing box preparatory to running ofi' on the web-forming device of a paper machine. Preferably at this point or subsequently, alkaline filler may be added to the diluted paper mix together with the size, or before or after the size. I prefer, however, that the size be added first and then the alkaline filler. ll may, however, in

certain cases, previously min the alkaline filler the size and add the mixture at the r vet end of the paper machine to the fibrous mix containing alum. in any case the alkaline tiller is preferably added in a continuous stream in aqueous suspension, suitably concentration of 23 lbs. per gallon, and the size in a dilute aqueous solution or emulsion conveniently at about 1-3 per cent. concentration. The broke and/or machine etduents containing alkaline tiller are preferably returned to the cycle at the end oi the paper machine in order not de stroy the alum in the alum-fibre mix, as "would occur contact therewith Was eiiected in the heater or chests.

There is another modification of my in vention which I find it convenient to practice at times, and that is a modification in some respects analogous to that disclosed my copending application Serial No. 440,645, filed March 31, 1930, wherein two separately prepared fibrous mixes, one containing sized fibre and the other containingunsized fibre and alkaline filler, are mixed at the wet end of the paper machine. In the present instance two fibrous mixes may be separately prepared, one containing fibrous material and alum, and the other containing fibrous material, alkaline filler, and size, and the two fibrous mixes fed separately to the mixing box. There are possible variations of this paper making flow-sheet which I have treated in detail in my copending application just referred to, and reference is made thereto concerning those variations, which are equally' applicable in the present instance. The fibre-alum mix in the present invention corresponds to the sized mix in the previously referred to application, whereas the size-alkaline filler-fibre mix inthe present invention corresponds to the unsized mix in the previous invention. The alkaline filler mix is preferably the one to which the machine broke and/or efiluents containing alkaline filler are returned.

' In regard to the modification of my invention mentioned immediately above, it may be pers.

also practiced by mixing alum with fibre to constitute one fibrous mix, mixing alkaline filler with fibre to constitute a second fibrous mix, and adding the two independent fibrous mixes, together with size in a separate stream, at the mixing box of a paper machine.

Relative to the amounts of materials to be used, the alkaline filler may be used in any amount customarily employed in filled pa- For example, in sized papers it is customary to use 8-15 per cent. by weight in the furnish, whereas in unsized papers the amount may be substantially higher, for example 25 to 30 per cent. In regard to alum, the amount will vary as will be apparent according to conditions but I have found that where substantially unsized paper is to be made, approximately 1 to 2 per cent. on the total furnish is usually a satisfactory amount. The amount of size in such case may be suitably' approximately .5 per cent. or thereabouts on the total furnish. IVhere sized paper is to be made, as will be readily understood the amount of size will vary with the type of paper to be ma de, machine conditions. and the like, but ordinarily it will be found that approximately 2 per cent. size will be ample, and alum in a proportion of 3 to 2 as regards size, is a convenient amount to use. It will be understood of course that the above figures are merely illustrative, and in no way limiting as I may practice my invention with proportions of ingredients varying widely from the above, and still obtain satisfactory results.

In my various copending applications referred to herein as well as in others, I have discussed in full the principle on which the expression minimizing the time and/or intimacy of contact of the constituents of the mix is based. Briefly it is that alkaline filler, which always is present in the stock from which paper filled with alkaline-filler is made in great stoichiometrical excess over the acidic constituent, acts uponthe acidic constituent to the ultimate destruction thereof and/or the destruction of the effect maintained by such constituent. (The acidic constituent socalled may be one which is actually acid, and/or one which such as a size precipitate is capable of being affected or deteriorated by an alkaline material.) The action just referred to has been found to depend upon the time of contact of the acidic and alkaline constituents and also upon theintimacy of contactof these constituents. A 'tation such as normally occurs in paperma ing procedure in'stuif chests or the like accelerates the rate of reaction, but agitation at low concentrations while having some effect is not nearly so deleterious. Based on this principle a practical application has been developed whereby, by minimizing the time and/or intimacy of contact of the acidic and alkaline constituents, the acidic constituent and/or the effect produced thereby, is substantially preserved in an alkaline filler mix. \Vith the present types of paper 'machines and the present arrangement of apparatus usually employed in paper machine operation, the contact of the acidic material and the alkaline constituent at any time prior to the passage of the stock from the last stufi' chest, which is commonly called the machine chest, results in great deterioration or complete destruction of the acidic material. Addition of one or both of these constituents at a point subsequent to the passage of the stock from the machine chest, after which point according to present day operating practice the stock remains in concentrated condition only for a very brief interval of time, or addition preferably at or subsequent to the point of dilution, i. e. at the wet end of the paper machine, serves to substantially conserve the acidic material and/or effect thereof in the fibrous mix. It is the application of this principle which I utilize herein in connection with the precipitation of the rosin size under conditions favoring the minimizing of the time and/or intimacy of contact of the constituents of the mix, e. g. at the wet end of the paper machine, and as shown by the above discussion this precipitate would be seriously deteriorated if not completely destroyed if the contact thereof with alkaline filler took place under other conditions, such as when the stock was in the concentrated condition. e. g. in the heater or stufi chests.

Cross reference is made to my copending application Serial No. 533,872, filed April 29,

1931, wherein in one modification of the invention disclosed therein, the procedure set forth herein, in the case where a non-acid compound of aluminum is additionally present, is described but not claimed.

For size I may use rosin size, or any size which may be used as a substitute therefor in the paper industry, such as saponified fatty acids or the like, or emulsions of various materials such as paraflin, or emulsions of other materials which may be substantially unaffected by alkaline filler.

Instead of alum, with a certain measure of success, I may use alone or in combination acidic materials, such as a mineral or other acids, particularly metallic salts such as comis, which will be on the alkaline side of theneutral point. Among fillers included in this group may be mentioned calcium carbonate, of which lime mud from the causticizing process is one form; calcium carbonate magnesium basic carbonate employed in the paper disclosed in my ll. S. Patent No. 1,595,416 of August 10, 1926; calcium carbonate magnesium hydroxide disclosed in my U. 55. Patent No. 1,415,391 of May 9, i922; and other substantially water insoluble normal or basic carbonates or alkaline earth metals, (which expression is herein intended to include magnesium}, or compounds, double Salts, or physically associated mixtures of these with one or more other acid soluble materials of a substantially water insoluble nature.

When I use the word paper herein, I use it in the broad sense include products of manufacture of all types and of all weights and thicknesses, which contain as an essential constituent considerable amount of prepared fibre which are capable ojl beproduced on a Fourdrinier, cylinder, or othe rforming, shaping or molding machine.

By the term wet end of the paper'machine, l intend to include instrumentalities employed paper m i which and/or in which a re Lion, such as the proportioning notic s, troughs, ns, head boxes, ets the like, iii-- also 1 is umentanties used in the It is to be understood that my invention is not dependent upon or limited by any theory expressed herein.

While I have described in detail the preferred embodiments of my invention, it is to be understood that the details of procedure, the proportions of ingredients, and the arrangement of steps may be Widely varied without departing from the spirit of my invention or the scope of the subjoined claims.

it claim:

1. The method of manufacturing paper filled with alkaline filler comprising mixing fibrous material and size precipitant, and adding to the resulting mix size and alkaline filler under conditions favoring the minimizing of the time of contact of the constituents of the mix, and thereafter making paper therefrom.

2. The method of manufacturing paper filled with alkaline filler comprising mixing fibrous material and size precipitant, and adding to the resulting mix size, in an amount insufficient to impart a substantial degree of sizing to the resulting paper, and alkaline filler under conditions favoring the minimizing of the time of contact of the constituents of the mix, and thereafter making paper therefrom.

3. The method of manufacturing paper filled with alkaline filler comprising mixing fibrous material and size precipitant, and adding to the resulting mix size and alkaline filler under conditions favoring the minimizing or" the time and intimacy of contact of the constituents of the mix, and thereafter making paper therefrom.

i; The method of manufacturing paper tilled with alkaline filler comprising mixing fibrous material and size precipitant, and adding to the resulting mix at the wet end of the paper machine size and alkaline filler, and thereafter making caper therefrom.

5. The method of manufacturing paper tilled with alkaline tiller comprising mixing fibrous material and size precipitant, and adding to the resulting at the wet end of the paper machine alkalineiiller previously mixed with other fibrous material, and size, and thereafter making paper therefrom.

The method of manufacturing paper filled with alkaline filler comprising mixing fibrous material and size precipitant, and adding to the resulting mix at the wet end of the paper machine alkaline tiller and size, previously with other fibrous material, and thereafter making paper therefrom.

'l. The method manufacturing paper filled with alkaline tiller comprising mixing fibrous material and size precipitant in a heater, and adding to the resulting mix alkaline filler and siize at the wet end of the paper machine, and thereafter making paper there filled with alkaline filler comprising mixing fibrous material and size precipitant, and adding to the resulting mix alkaline filler and size, in an amount insuflficient to impart a substantial degree of sizing to the resulting paper, at the wet end of the paper machine, and thereafter making paper therefrom.

9. The method of manufacturing paper filled with alkaline filler comprising mixing fibrous material and acidic material, and add-' ing to the resulting mix alkaline filler and size at the wet end of the paper machine, and thereafter making paper therefrom.

10. The method of manufacturing paper filled with alkaline filler comprising mixing fibrous material and metallic salt, and adding to the resulting mix alkaline filler and size at the wet end of the paper machine, and thereafter makin paper therefrom.

11. The metho filled with alkaline filler comprising mixing fibrous material and salt of aluminum, and adding to the resulting mix alkaline filler and size at the wet end of the paper machine, and thereafter making paper therefrom.

12. The method of manufacturing paper filled with alkaline filler comprising mixing fibrous material and alum, and adding to the resulting mix alkaline filler and size at the wet end of the paper machine, and thereafter making paper therefrom.

13. The method of manufacturing paper filled with alkaline filler comprising mixing fibrous material and size precipitant, and adding to the resulting mix alkaline filler and rosin size at the wet end of the paper machine, and thereafter making paper therefrom.

14. The method of manufacturing paper filled with alkaline filler comprising mixing fibrous material and alum, and adding to the resulting mix alkaline filler and rosin size at the wet end of the paper machine, and thereafter making paper therefrom.

15. The method of manufacturing paper filled with alkaline filler comprising calcium carbonate, comprising mixing fibrous material and size precipitant, and adding to the resulting mix alkaline filler and size at the wet end of the paper machine, and thereafter making paper therefrom.

16 The method of manufacturing paper fille with alkaline filler comprising calcium carbonate and magnesium compound, comprising mixing fibrous material and size precipitant, and adding to the resulting mix alkaline filler and size at the wet end of the paper machine, and thereafter making paper therefrom.

17. The method of manufacturing paper filled with alkaline filler comprising calcium carbonate magnesium hydroxide, comprising mixing fibrous material and size precipitant, and adding to the resulting mix alkaline filler and size at the wet end of the paper of manufacturing paper ifnachine, and thereafter making paper thererom.

18. That improvement in the manufacture of paper filled with alkaline filler comprising the addition of alkaline filler and size to a paper mix under conditions favoring the minimizing of the time of contact of the constituents of the mix.

19. That improvement in the manufacture of paper filled with alkaline filler comprising the addition of alkaline filler and size to a paper mix under conditions favorin the minimizing of the time and intimacy 0 contact of the constituents of the mix.

20. That improvement in the manufacture of paper filled with alkaline filler comprising the addition of alkaline filler and size to a paper mix at the wet end of the paper machine.

21. That improvement in the manufacture of paper filled with alkaline filler comprising the addition of alkaline filler and rosin size to a paper mix at the wet end of the paper machine.

22. That improvement in the manufacture of paper filled with alkaline filler comprising the addition of alkaline filler and size to a previously acidified paper mix at the wet end of the paper machine.

In testimony whereof I afiix my signature.

HAROLD ROBERT RAFTON. 

